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| 2. |
- Ojeda, M., et al.
(författare)
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Synthesis of Rh nano-particles by the microemulsion technology - Particle size effect on the CO+H-2 reaction
- 2004
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Ingår i: Applied Catalysis A. - : Elsevier BV. - 0926-860X .- 1873-3875. ; 274:1-2, s. 33-41
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Tidskriftsartikel (refereegranskat)abstract
- Several alumina-supported rhodium-based catalysts have been prepared using the microemulsion technology. The change of microemulsion properties led to catalysts with different Rh particle size and narrow size distribution while keeping the same metal loading. The metal particle size was determined by XRD and TEM. These catalysts were tested in the CO hydrogenation reaction in order to investigate the influence of the Rh particle size. The catalytic results indicated that turnover frequency (TOF) increased about four times when the Rh particle size increased approximately from
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| 3. |
- Rojas, Ana Maria, et al.
(författare)
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Is sensitization with nicotinamide and carbogen dependent on nicotinamide concentration at the time of irradiation?
- 2004
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 80:7, s. 499-506
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To determine whether tumour radiosensitization and the therapeutic benefit of administering carbogen with nicotinamide depend upon irradiating at the time of peak drug concentration. MATERIALS AND METHODS: Local tumour control of CaNT tumours in CBA mice and acute skin reactions in albino WHT mice were assessed after treatment with 10 X-ray fractions in air, carbogen alone or combined with 0.1, 0.2 or 0.5 mg g(-1) nicotinamide, injected 15, 30 or 60 min before irradiation. Plasma and tumour drug pharmacokinetics were performed. RESULTS: Nicotinamide was rapidly taken up into tumours; a six- and threefold higher concentration was obtained with 0.5 mg g(-1) compared with 0.1 and 0.2 mg g(-1), respectively. Tumour, but not skin, radiosensitization increased as the dose of nicotinamide increased (p = 0.03), but at each dose level there was no significant difference in radiosensitivity when irradiations were done at or after the time of peak concentration. An almost eightfold increase in plasma levels increased tumour enhancement ratios from 1.74 to 1.92 (p < 0.0001). In tumours all schedules gave significant enhancement relative to carbogen alone (p < or = 0.04). CONCLUSIONS: Tumour and skin radiosensitivity was independent of time of nicotinamide administration. Higher drug concentrations were not mirrored by proportionally higher enhancement ratios. Lower plasma levels than previously suggested significantly enhanced tumour radiosensitivity relative to carbogen alone. The clinical implications of these findings are discussed.
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| 4. |
- Thors, Björn, et al.
(författare)
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The RCS of a clylindrical array antenna coated with a dielectric layer
- 2004
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 52:7, s. 1851-1858
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Tidskriftsartikel (refereegranskat)abstract
- The scattering properties of dielectric coated waveguide aperture antennas mounted on circular cylinders are investigated. Both the single element antenna and the array case are treated. The array antenna consists of 4 x 32 rectangular apertures placed in a rectangular grid on the surface of an infinitely long circular cylinder. The problem is formulated in terms of an integral equation for the aperture fields which is solved with the method of moments using rectangular waveguide modes as basis and test functions. An efficient uniform asymptotic technique is used to calculate the excitation vector and the backscattered far-field. The asymptotic solution is valid for large cylinders coated with thin dielectric layers away from the paraxial (i.e. near axial) region. A similar asymptotic solution is used to calculate the mutual coupling in the nonparaxial region. For the self coupling terms and for the mutual coupling in the paraxial region a planar approximation is used with a corresponding spectral domain technique. Numerical results are presented as a function of frequency, angle of incidence, cylinder radius, and electrical thickness of the coating.
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